Many wept openly during the funeral services in St. Mary's Church for the young friends.
"The city's hearts really go out to the parents of these kids," said Lawrence Mayor Michael Sullivan. "There aren't words big enough to make the hurt go away."
One mother wailed in grief as she followed her son's casket into the church. Another collapsed during the services.
William Rodriguez, 11; Christopher Casado, 7; Mackendy Constant, 8;, and Victor Baez, 9, died Saturday after falling through thin ice on the Merrimack River.
Three other boys -- Casado's brother Ivan, 9; Jaycob Morales, 10; and Francis Spraus, 9 -- survived.
Rodriguez was the first to fall through the weakened ice about 25 feet from the riverbank. The other six formed a human chain in an attempt to rescue him. They also fell in, but Morales and Spraus were rescued after Ivan Casado, closest to shore, was able to get out of the 35-degree water and go for help.
School Superintendent Wilfredo LaBoy spoke of the boys' heroism at the church.
"All of the teachers felt the boys had such presence at the school," he said, "and none of them, when told the sad news, was surprised that they would risk their own lives to save one another."
Sullivan also spoke about the boys' heroic rescue attempt. He called the way the boys formed a human chain "sort of a wonderful story."
More than 6,000 people turned out through Wednesday night to pay their respects to the four young friends who lay in matching white coffins.
Many mourners were classmates of the victims, seeing death first hand for the first time. Some reached out to touch the faces and hair of the boys, all dressed in suits.
"So many young, beautiful kids," said Rep. Martin Meehan, D-Mass., whose district includes Lawrence. "It's devastating to the families. It's horrible to the community."
Sen. Edward M. Kennedy, D-Mass., and Sen. John Kerry also paid their respects.
Funds have been established to help the families.